Tag Archives: Testing Period

How to Determine if You Used the HSA Last Month Rule


This is a fairly common question I get from readers regarding the HSA’s Last Month Rule and how to file Line 18 on Form 8889. The question usually takes the form of:

  • “Did I use the Last Month Rule last year?”
  • “Do I owe anything for the Last Month Rule?”
  • “What should I put on Line 18 of Form 8889 where it says Last Month Rule?”

Luckily, it should be easy to figure out whether the Last Month Rule even applies to your tax return. The goal of this article is to explain how the Last Month Rule works, and then ask 3 questions to see how it applies to you.

What is the Last Month Rule?

Let’s start by defining some terms. The Last Month Rule is a “feature” of HSA’s that generally only applies to a year that you begin HSA eligible coverage. It states that if you are an eligible individual as of December 1st of a year, you are treated as an eligible individual for that entire year. This is a benefit as it allows you the option to contribute that year’s full contribution limit instead of a pro-rata amount. You get more tax free medical spending.

As an example, assume I began coverage on June 1st, 2016. Normally, I would only be able to contribute 7/12 (Jun, Jul, Aug, Sep, Oct, Nov, Dec) or just over half of the contribution limit for that year. But since I had coverage on December 1st, I am treated as an eligible individual for the whole year and may contribute up to the full contribution limit.

What is the Testing Period?

However, there is a catch. If you take advantage of the Last Month Rule and choose to contribute more than you normally could have (e.g. 12/12 vs 7/12 above), you are bound by the Testing Period to maintain that coverage for the following year. If you do not, any contribution above the 7/12 you were allowed is considered excessive and taxed and penalized on Line 18 of Form 8889 when you file your taxes. This is generally not good and should be avoided.

Please see this article for a more complete description of the Last Month Rule and Testing Period.

Determining if the Last Month Rule applies to you

First off, let’s relieve a lot of people from worry: if you had the same HSA coverage for each month in a tax year, you can put “0” on Line 18 of Form 8889. Since the Last Month Rule applies only to those who began or changed coverage, you can ignore it and likely go onto something else more enjoyable.

If you had consistent HSA eligible insurance for each month of the year, the Last Month Rule does not apply and you can put “0” on Line 18 of Form 8889.

On the other hand, if you began or changed HSA coverage this year, let’s pose three “yes” or “no” questions to help determine if the Last Month Rule applies to you. You must answer “yes” to the following 3 questions to be eligible to use the Last Month Rule. Answering “no” to any of the following means you can only contribute the pro-rata contribution amount for the months you were HSA eligible.

1) Were you an eligible individual (have HSA eligible coverage) on December 1st of the tax year?

Answering “no” precludes you from using the Last Month Rule as it is a base requirement. This rules out people who, for example, had coverage from January – November of a year, or had coverage from February until August of a tax year. You at least have to have coverage in December to be eligible for the Last Month Rule.

If you answered “yes”, then you may be eligible to use the Last Month Rule, read on.

2) You were HSA eligible (had HSA coverage) for only part of the year?

Answering “no” means you had coverage for the full year, so by definition you can already contribute the HSA maximum contribution limit. You had coverage for 12 months, so can contribute 12/12 or 100% of the contribution limit for the year. You don’t need the Last Month Rule’s help. If this applies to you, put “0” on line 18 of Form 8889.

If you answered “yes”, you likely began coverage mid-year. Perhaps you got a new job and had HSA qualified starting on April 1st, so 9/12 months of the year. Or you had coverage for January through April, then stopped, then had coverage for November and December. If this sounds like your situation, this means that you have the option of using the Last Month Rule for that year. To actually use it, move on to question #3.

3) Did you contribute more than you would otherwise be allowed?

Answering “no” means you contributed less than or equal to your contribution limit based on your months as an eligible individual. So if you had HSA coverage for 5 months, you are allowed to contribute up to 5/12 (41.6%) of the contribution limit without using the Last Month Rule. Doing so plays it safe and avoids any of the requirements or risk of penalty associated with the Testing Period.

Answering “yes” sounds like, “I had HSA coverage for 7/12 months but I contributed the maximum contribution limit using the Last Month Rule”, or “I had coverage for 3/12 months (Oct / Nov / Dec or 25%) but contributed 1/2 (50%) of the maximum contribution limit.” In both of these scenarios, you contributed more to your HSA than you would generally be allowed. This is allowable, as you leveraged the Last Month Rule to make an increased contribution, but remember it has strings attached.


If you answered “No” to any of the 3 questions above, you cannot use the Last Month Rule. You will need to contribute your pro-rata contribution limit based on the number of months you were HSA eligible. You can also put “0” on Line 18 of Form 8889.

If you answered “Yes” to all 3 questions above, you used the Last Month Rule and contributed more than you generally could have. This is allowable but remember you need to maintain HSA coverage for the next year due to the Testing Period. For the current year, you can put 0 on Line 18. If you maintain that HSA coverage through the following year, you will also put “0” on Line 18 of that year’s Form 8889, pass the Testing Period, and hopefully never worry about the Last Month Rule again. Only if you don’t maintain coverage (i.e. fail the Testing Period) will you need to calculate a penalty for Line 18, which will increase your taxable income and add a penalty to your 1040 return.

Note: if this is super confusing, please consider using my service EasyForm8889.com to complete Form 8889. It asks these questions in a straightforward way and will generate your HSA tax forms in 10 minutes. It is fast and painless, no matter how complicated your HSA situation.

EasyForm8889.com - complete HSA Form 8889 in 10 minutes!

Deciding to Use the Last Month Rule for New HSA Coverage

This question was submitted by HSAedge reader Beth. Feel free to submit your question today to evan@hsaedge.com.

I have an employer that is implementing an HSA eligible plan on 4/1/2017. Of course, everyone wants to invoke the “last month rule” but we keep telling them that is not a best practice due to the possible tax implications should they switch plans etc. Can you give some examples of “problems” with someone enrolling 4/1/2017 invoking the last month rule and not remaining covered during the testing period?

That is certainly a good question and applies to many people who begin HSA coverage mid year. As I see it, they have two options in front of them – reduce their contribution pro rata for the months covered, or contribute the full year amount by using the Last Month Rule. The former is safe with no risk of paying taxes and penalties in the following year, while the latter allows you to contribute more in the current year.

Contribute Only for Months Covered to Lower Risk

Let’s be clear on the situation facing your team. With coverage beginning on April 1st 2017, they will have 9 months of HSA eligible coverage for 2017. Stated differently, they are covered by a HSA eligible insurance for 75% (9/12) of 2017. Since they only have partial year coverage, the amount they can safely contribute to their HSA that year is reduced pro rata. In this case, they can contribute 75% of the contribution limit based on their coverage type and age, no strings attached. For 2017, these amounts are:

  • Self only: $3,400 x 0.75 = $2,550
  • Family: $6,750 x 0.75 = $5,062.50
  • if 55+: $1,000 x 0.75 = $750 in addition to above

So they can contribute those amounts, free and clear, and be finished. Making contributions for the months you had HSA eligible coverage means you never have to worry about taxes or penalties relating to the Last Month Rule.

Contribute More Using Last Month Rule

However, they may be aware that there is a provision called the Last Month Rule that states that if they have HSA eligible insurance on December 1st of a year, that they can contribute the full year contribution limit. Assuming they maintain HSA eligible coverage until December, this election allows them to contribute 100% of the $3,400 or $6,750, instead of just 75%. However, what they may not know is there is a catch. By taking advantage of the Last Month Rule, they are bound by the terms of the Testing Period. This basically states that they need to maintain HSA coverage for the following 12 months, or the amount they contributed above their calculated (75%) amount will be taxed and penalized.

People fail the Testing Period more often than you think, and it causes tax problems when they go to file Form 8889. It is difficult to predict over a year in advance what your insurance situation will be. Some events are not foreseeable. Other people don’t even know what the Testing Period is! For example, here are some common reasons people’s insurance changes and they fail the Testing Period:

  • Change jobs and get new insurance
  • Lose job and lose insurance
  • Change to a non HSA-eligible plan
  • Go onto spouse’s insurance
  • Change to state health insurance (Obamacare)
  • Go onto Medicare
  • Start taking Social Security

Any of the above will likely cause you to fail the Testing Period and owe taxes and penalties.

Calculating Taxes and Penalties for Failing the Last Month Rule

If you fail the Testing Period, you will have to go back and do a bunch of work for Form 8889. The IRS will have you compare the amount you contributed ($3,400 or $6,750) to the amount you could have contributed without the Last Month Rule ($2,550 or $5,062.50). The difference will be added to your taxable income for the current year and assessed a 10% penalty.

Here are the tax and penalty calculations for our previous examples. Assume you had 9 months of coverage and used the Last Month Rule to contribute the full 2017 contribution limit:

  • Self only: $3,400 – $2,550 = $850 added to income (taxed); $85 penalty
  • Family: $6,750 – $5,062.50 = $1,687.50 added to income (taxed), $168.75 penalty
  • if 55+: $1,000 – $750 = $250 added to income (taxed); $25 penalty in addition to above

As you can see, failing the Testing Period means writing Uncle Sam a check for taxes and penalties. For some people, this is a bad bet because they change insurance frequently, or the taxes / penalties / headache aren’t worth the additional risk. They contribute a little less this year but no big deal. For others, this is a good risk because they have stable insurance. It allows them to contribute more to their HSA and reduce current year taxes. There is no “right” answer and it is up to the individual HSA holder to decide.

How to File Form 8889 For Your Old HSA Funds When You No Longer Have HSA Coverage

This was a reader question submitted by HSA Edge reader Beata. If you have a question get in touch and we’ll try to help. Email us at evan@hsaedge.com any time.

I was no longer under the High Deductible Plan with my new employer in 2017, however I had some left over funds in my HSA account from my previous employer. No contributions were made in 2016.

I used up all the funds in 2016 for qualified medical expenses. Do I skip parts I and III on the form and just fill out part II about the distributions?


This is a pretty common scenario that occurs as life goes by and people change insurance coverage. Frequently, people who previously had and contributed to an HSA eventually change coverage to a non-HSA eligible plan, due to a job change, insurance change, or life event. One of the great benefits of Health Savings Accounts is that the money remains yours forever, even if your coverage changes. This contrasts with other health plans like FSA’s where there is a “use it or lose it” clause on the plan, forcing you to predetermine a contribution amount and spend it in the year. Thus, the good news is you still have your HSA funds to spend on qualified medical expenses, but how do you file HSA tax Form 8889?

If You Spent Funds, You Need to File Form 8889

First things first, you definitely need to file Form 8889 if this situation applies to you. Even if you had the HSA plan 10 years ago, and are no longer contributing to the account, as long as you are spending funds from the HSA the government wants to know about it. The hard and fast rule is if money is going into or out of your Health Savings Account, you need to file Form 8889 for the tax year in which that spending occurred. This form is due by your tax filing deadline, and can be extended if extension is filed. It will be best just to file it with your regular taxes.

Note that if you don’t contribute to or withdraw from an HSA in a given year, you likely do not need to file Form 8889 for that year.

What follows is a summary discussion of filing Form 8889 if you no longer have HSA coverage but spent old HSA funds this year. More detailed information can be found about How to File Form 8889.


Part I – Contributions

Form 8889 consists of 3 parts, and the first one should be fairly straightforward. It’s main focus is determining your contribution limit and the amount you (and others) contributed during the year. Since the topic of this post is that you no longer have HSA coverage (but have funds in an HSA account), you will neither have 1) a contribution limit or 2) (allowable) HSA contributions. As such, this section will be all $0’s, which logically follows that your deductible amount (Line 13) will also be $0 and flow over as such to Form 1040.

Part II – Distributions

The second part of Form 8889 details the funds that exited your HSA, and this is where you will have to do some work. Line 14a and 15 are the main tasks here, and they are asking “How much exited your HSA” and, “How much did you spend on Qualified Medical Expenses?”. Ideally, both of these amounts should be the same: any money I withdraw from my HSA should be spent appropriately. If that is the case, you will face no taxes and penalties, but as you can see in subsequent lines 16 and 17b, any delta between those numbers will be taxed and penalized.

This 2016 Form 8889 was prepared by EasyForm8889.com.


Part III – Taxes & Penalties

Part 3 of Form 8889 involves a calculation of various taxes and penalties you might owe. These can arise from failure to comply with the Testing Periods set forth in the Last Month Rule and Qualified Funding Distributions. Hopefully, these do not apply to you if you are simply spending remaining funds from an old HSA. If so, this section will be blank and you can just add $0’s there as well.

However, if you recently ended insurance and in the prior year 1) utilized the Last Month Rule to increase your contribution or 2) utilized a Qualified Funding Distribution from a IRA/Roth IRA, you could be in trouble. Both of these contain a Testing Period that stipulates continued HSA eligibility conditional with their use, in an effort to prevent tax abuse. If you fail to maintain coverage for the specific Testing Period, your contribution is considered “excessive” and will be taxed and penalized for the tax year in question. It is best to fully understand these rules before engaging them, and if you are facing a penalty, thoroughly review how they are calculated or use a service like EasyForm8889.com.